#include<stdio.h>
int Fib(int n)
{
	if (n <= 2)
	{
		return 1;
	}
	else
	{
		return Fib(n - 1) + Fib(n - 2);
	}
}
int main()
{
	int n = 0;
	scanf_s("%d", &n);
	int ret = Fib(n);
	printf("%d", ret);
}